.\" Copyright (c) 2013, Luiz Otavio O Souza <loos@FreeBSD.org>
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.Dd May 23, 2019
.Dt GPIOLED 4
.Os
.Sh NAME
.Nm gpioled
.Nd GPIO LED generic device driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device gpio"
.Cd "device gpioled"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides glue to attach a
.Xr led 4
compatible device to a GPIO pin.
Each LED in the system has a
.Pa name
which is used to export a device as
.Pa /dev/led/<name> .
The GPIO pin can then be controlled by writing to this device as described
in
.Xr led 4 .
.Pp
On a
.Xr device.hints 5
based system, like
.Li MIPS ,
these values are configurable for
.Nm :
.Bl -tag -width ".Va hint.gpioiic.%d.atXXX"
.It Va hint.gpioled.%d.at
The gpiobus you are attaching to.
Normally assigned to gpiobus0.
.It Va hint.gpioled.%d.name
Arbitrary name of device in
.Pa /dev/led/
to create for
.Xr led 4 .
.It Va hint.gpioled.%d.pins
Which pin on the GPIO interface to map to this instance.
Please note that this mask should only ever have one bit set
(any other bits - i.e., pins - will be ignored).
.It Va hint.gpioled.%d.invert
Use pin inversion. If set to 1, the pin will be set to 0 to light the LED, and 1
to clear it.
.It Va hint.gpioled.%d.invmode
Whether or not to use hardware support when pin inversion is requested. Must be
one of:
.Bl -tag
.It Va auto
Use hardware pin inversion if available, else fallback to software pin
inversion. This is the default.
.It Va hw
Use hardware pin inversion.
.It Va sw
Use software pin inversion.
.El
.It Va hint.gpioled.%d.state
The initial state of the LED when the driver takes control over it.
If set to 1 or 0, the LED will be on or off correspondingly.
If set to -1, the LED will be kept in its original state.
.El
.Pp
On a
.Xr FDT 4
based system, like
.Li ARM ,
the DTS part for a
.Nm gpioled
device usually looks like:
.Bd -literal
gpio: gpio {

	gpio-controller;
	...

	led0 {
		compatible = "gpioled";
		gpios = <&gpio 16 2 0>;		/* GPIO pin 16. */
		name = "ok";
	};

	led1 {
		compatible = "gpioled";
		gpios = <&gpio 17 2 0>;		/* GPIO pin 17. */
		name = "user-led1";
	};
};
.Ed
.Pp
Optionally, you can choose to combine all the LEDs under a single
.Dq gpio-leds
compatible node:
.Bd -literal
simplebus0 {

	...

	leds {
		compatible = "gpio-leds";

		led0 {
			gpios = <&gpio 16 2 0>;
			name = "ok"
		};

		led1 {
			gpios = <&gpio 17 2 0>;
			name = "user-led1"
		};
	};
};
.Ed
.Pp
Both methods are equally supported and it is possible to have the LEDs
defined with any sort of mix between the methods.
The only restriction is that a GPIO pin cannot be mapped by two different
(gpio)leds.
.Pp
For more details about the
.Va gpios
property, please consult
.Pa /usr/src/sys/dts/bindings-gpio.txt .
.Pp
The property
.Va name
is the arbitrary name of the device in
.Pa /dev/led/
to create for
.Xr led 4 .
.Sh SEE ALSO
.Xr fdt 4 ,
.Xr gpio 4 ,
.Xr gpioiic 4 ,
.Xr led 4
.Sh HISTORY
The
.Nm
manual page first appeared in
.Fx 10.1 .
.Sh AUTHORS
This
manual page was written by
.An Luiz Otavio O Souza .
